Method of making bifocal lenses.



PATENTED SEPT. 10, 1907;

0. F. DIEGKMANN. METHOD OF MAKING BIFOGAL LENSES.

APPLIOATION FILED JULYZ 1907 UNITED srAr-Es PATENT orrrcn- CARL F. DIEOKMANN, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO KRYPTOK-COMPANY, A CORPORATION OF NEW'YORK.

METHOD OF MAKING- IBIFOCAL LENSES.

Specification of Letters Patent.

Patented Sept. 10, 19.67.

Application filed July 2,1907. 'SerialNo. 381,894.

To all whom it may concern: I

Be it known that I, CARL F. DIECKMANN, acitizen of the United States, residing at New York city, in the county of New York and State of New York, have invented certainnew and useful Improvements in Methods of Making Bifocal Lenses, of which the'following is a full, clear, and exact description.

My invention relates to the manufacture of bi-focal lenses, or the preparation of the blank therefor, and

consists in the'nature and sequence of thesteps and operations by which separate properly formed pieces .of glass of different indices'of refraction maybe perfectly welded or united'together into a single, unitary or solid v lens.

Lenses of the above character are now commonly manufactured in a number of different ways, but so far as 1 am aware, difficulty has been generally experienced by reason of gas, steam and air bubbles which are trapped between'the surfaces of the separate pieces at the time theyare welded. This difficulty probably arises on account of the hydroscopic nature of glass which attracts moisture toits surface from the air, and also the fact that all solid bodies carry on their surfaces a thin film of air which closely adheres thereto. The effect is particularlypronounced where the separate glass pieces are ground to the same curvature so that they fit closely when they are being welded. By the present inven-- tion this'difiiculty-is overcome, and by the following steps and operations, particularly illustrated in theaccompanying drawings, in which,

Figure l is a sectional view showing the glass pieces about to be assembled and welded. Fig. Zis a similar view showing the same at the first stage ofthe operation. Fig. 3 is a top or plan view of the same. Fig. 1 illustrates'the next stage of the bperation. Figs. 5 and 6 show the two succeeding operations or stages. Fig. 7 shows one of the glass pieces having a slightly different shape. Fig. 8 shows the first stepof my proc'essas employed therewith. Fig.9 illus'trates'a'part used in this embodiment of the process. I

Referring to the drawings in which like parts are designated by the same'reference sign, A indicatesapicce of glass for a lens and which may be termed the main different index of refraction, and which'rnay be termed the supplemental'blank or lens. Tlie blank A is first ground with a depression (J, the curvature of which is i suited to the requirements of the finished 'product,'as hereinafter described. The blank B is superposed on the main blank A, but is'not allowed" to fit or rest closely D. In practice, I'have employed a small bit of steel B indicates another piece of glass of,

for this purpose. The essential thing is to have the supplemental blank B held away from the main blank A at one or more points, and it is evident that this may be accomplished in any suitable manner.

The next step of the process is to apply heat to the assembled blanks so as to bring them to'a welding temperature, or, more properly, a temperature at which they adhere, which is slightly below What is ordinarily known as a welding temperature. Under these cire'umstances, the blank B commences to merge into and adhere upon the surface of the blank A in the manner shown in Fig; 4. This welding action or adhesion occurs initiallywhere there is contact between the glass pieces, and from this point or points the union spreads in the direction or directions of those points where the blanks are held apart, for example by the body or bodies 1). Thus the union or adhesion spreads from a single point or points throughout the entire surfaces to be united, and ends ata predetermined or desired place Where the surfaces were supported apart. Thc latterpoints are preferably near the circumferential edges of theparts to be joined, so that the gas, air and steam which is driven off by the heating is gr'adually'crowded outward and away from the growing ment and rhctermination of the union or adhesion at such points or areas that there is always a vent for the gas, air and steam. The action is to have the area of union start at a single point of contact between the blanks, and constantly grow and enlarge from such point successively toward the circumferential point or points where the blanks are supported apartto 'form a vent, finally welding or uniting here also, after 'the gases are'expelled and'the blanks are united at every other point,

IiiFigs. 7 and 8, a supplemental blank B is employed which is initially ground to conform to the curvature of the doprcssionC. This is in some cases advantageous sincc-it'relicvcs this blank of the necessity of bending and conforming to a different shape. In this form ofthe invention the blanks may be supported apart by a circumferential ring E with a gap F through which the gases may escape. In this form of the invention, the welding or union obviously commences atthe center and cnlarges outward therefrom, instead of conimencing at an eccentric or circumfercntialpoint and enlarging outward therefrom as with the first described embodiment of this invention.

The blanks or lenses being completely'united in the manner shownin Fig. 5,'it is merely necessary to grind and polish the resultant product into a solid lens as shown in Fig. 6, and cut it into any desired form for eyeglasses or other purposes. The foreign body D-is ground away and eliminated in the grinding and shaping process.

What I claim is:

l. The process of welding or uniting together blanks for bi-focal lenses, which consists in supporting them in spaced apart relation by means independent of the blanks themselves and subjecting them to a welding or uniting temperature, whereby one of the blanks is caused to soften and settle down upon and adhere to the other.

2. The process of welding or uniting together blanks for bi-focal lenses, which consists in supporting them in spaced apart relation by an intermediate foreign body, and subjecting them to a welding or uniting temperature. whereby one of the blanks is caused to soften and settle down upon and adhere to the other.

3. The process of welding or uniting together blanks for bi-focal lenses, which consists in supporting them in spaced apart relation by an intermediate foreign body at the circumference of one of the blanks, and subjecting them to a welding or uniting temperature, whereby one of the blanks is caused to soften and settle down upon and adhere to the other. I

4. The process of making bi-focal lenses, which consists in grinding a blank to form a depressed portion thereon, supporting a supplemental blank in spaced apart relation therefrom at one or more points by means independent of the blanks themselves, and subjecting the blanks to a weld ing or uniting temperature whereby one of the blanks is caused to soften and settle down upon and adhere to the other, and grinding and polishing the resultant product.

5. The process of making bi-focal lenses, which consists in grinding a blank to form a depressed portion thereon, supporting a supplemental blank in spaced apart relation therefrom at one or more points by an intermediate foreign body, subjecting the blanks to a welding or uniting temperature whereby one of the blanks is caused to soften and settle down upon and adhere to the other, and grinding and polishing the resultant product.

6. The process of welding or uniting together blanks for bifocal lenses, which consists in grinding a blank to form a depressed portion thereon, supporting a supplemental blank in spaced apart relation therefrom at one or more points near the circumference by an intermediate foreign body, subjecting the blanks to a'welding or uniting temperature, whereby one of the blanks iscaused to soften and settle down upon and adhere to the other and grinding and polishing the resultant product.

i In witness whereof, I subscribe my signature, in the presence of two witnesses.

CARL. .F. .DIECKMANN.

Witnesses CARL Jussnn, Gno. E. KELLNER. 

